Annunciator-board and circuit for telephone-exchanges



(No Model.) 2 sneets sneet'a M. C; KELLoCC. ANNUNCIATCE BOARD ANDCIRCUIT FOR TELEPHONE EXCHANGES. C No. 258.284. PatentedMayZB, 1882minqs ses I I V Jil n-nay N. PETERS, Phulo-Lilhogmphor. Wishinglnn. D.C.

To all whom it may concern:

- IUNITED STATES PATENT ()FFICE.

MILO Gr. KELLOGG, OF HYDE PARK, ASSIGNOR TO THE WESTERN ELECTRICMANUFACTURING COMPANY, OF CHICAGO, ILLINOIS.

ANNUNCIATOR-BOARD AND CIRCUIT FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 258,234, dated May 23,1882.

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Be it known that I, MILO G. KELLOGG, of Hyde Park, county of Cook,Illinois, and doin g business in Chicago, in said State, have discovered certain new and useful Improvements in Annunciator-Boards andCircuits of Telephone-Exchan ges, of which the following is a full,clear, concise, and exact description.

In the drawings, Figure 1, Sheet 1, Ais the switch-board at the centraloffice. B and B are annunciator-boards. Fig. 2 is a detail section of amodified form of the jack-knife switch. Fig. 3, Sheet 2, is a diagram ofthe circuits of the telephone-lines from the switch-board to theannunciator-boards. Fig. t is a detail of 'a connecting-bolt.

The telephone-lines a a a? u e, &c., are connected in any well-known wayat the stations of the subscribers, and converge to the central office,where they are connected with their respective switches b1) b b I),&c.,on the switchboard A in the usual manner. The lines are now dividedinto groups, each group containing as many lines as can be convenientlyattended to upon an annunciator-board. The number of groups will dependupon the size of the exchange and the demands of the subscribers. Anexchange of five hundred subscribers should be provided with fiveannunciatorboards under ordinarycircumstances, while an exchange of athousand subscribers would require from eight to ten annunciator-boardsunder the same conditions. An attendant is stationed at eachannunciator-board, and one or more switch men at the switch-board. Theseveral telephone-lines run through their respective switches on theswitch-board and through their respective annunciators on theannunciator-boards, and thence to ground, so that the call of a givensubscriber is received by the attendant at the annunciator-board uponwhich is placed said subscribers calling-annunciator. When the attendanthas received a subscribers order he informs the switchman whatconnection is wanted, and the switchman connects the switch of thecalling subscriber with the switch of the subscriber called for througha c1earing=out annunciator in the usual manner.

Application filed April 4, 1881. (No model.)

Lines a and a are shown thus connected by means of flexible cords andplugs. When the plugs are inserted, as shown, the annunciators andground-connections are automatically removed. On removing the plugs thenormal circuits of the lines are restored, and the subscribers areenabled to send in their calls, as 5 5 before indicated.

The normal circuit of line a may be traced as follows: from switch I) byline 0 to connecting-bolt d, and thence by line 0 to the armature f ofthe calling-annunciator of the line, and thence through the drop orshutter g to line h, and thence through the electro-magnet iand by line70 to ground. When a. current is sent over this circuit from line a theshutter 9 falls, and the attendant at board B is thereby notified of thecall. The attendant thereupon connects his telephonel into the circuitin any suitable manner, preferably by holding plug m against theconnecting-bolt d. The whole circuit of line a may be thus directedthrough theitelephone of the listening attendant at annunciatorboard B.The subscriber and attendant are thus in direct communication, and thesubscriber gives the name of the one with whom he wishes to speak.

The normal circuit from theconnectingbolt, instead of passing throughthe armature and shutter, may pass directly through the electromagnet,in which case the ground'wonld'not be taken off automatically when theshutter 86 falls, and the circuit passing through the telephone would bea derived circuit. A circuit thus derived would be sufficient for allpractical purposes.

A listening attendants outfit and callingbattery n is provided at theswitch-board. When two subscribers are connected, as shown,

a current is sent to line by depressing key 0. The subscriber called foris thus summoned, while the caller is notified that the ofiice is dogoin g its duty. By connecting the key 10 to line a,- as shown, anddepressing the key 0 the clear ing-out annunciator may be used toindicate whether the line called for-that is to say, line a-is open orclosed. In case both subscribers 5 should forget to send in theclearing-out sig nal the listening operator by depressing key 19 may taptheir circuit, and by means of the derived circuit passing through histelephone q determine whether the subscribers have stopped talking.

By the use of my system it will be seen that a large exchange may hesuccessively worked upon a single switch-board, the duty of theswitchnien being confined to connecting and disconnecting the switchesin response to the orders of the attendants at the annunciator boards.In case a subscriber called for is already connected the switchman seesthe plug inserted in his switch and the caller is notified that the oneasked for is busy, and thus all confusion is avoided.

I claim- 1. In a telephone-exchange, two lines connected together forconversation, in combination with two keys, one of which, on being(lepressed, grounds the lines through the centraloftice telephone, andthe other of which, on being depressed, grounds the lines through thecentral-office signaling-battery.

2. In a telephoneexchange, the combination of a switch-board at thecentral oftice, provided with spring jack-switches, one switch for eachline which enters the central oflice, two or more annunciator-boards,upon which the lines are grouped, annunciators upon each of theannunciator-boards, one annunciator for each line of the group, and.telephone-lines, each line passing first to its switch on theswitchboard, thence to its annunciator of its group, and to ground,whereby an annunciator of a group is disconnected from its line when aline is connected atthe switchboard with another line, substantially asshown and described.

3. In a telephone-exchange system, the combination of two linesconnected together for conversation, a clearing-out annunciator in thecircuit of said lines, and a battery and callingkey at the centraloftice, so connected that when the calling-key is operated so as tosignal to line the clearing-out annunciator responds or indicates thatthe signal has been sent.

4. In a telephone-exchange system, the combination, at the centraloffice, ot' a switch-board at which is performed the switching betweenall the lines which center at the office, two or morecalling-annunciator boards, among which the wires are grouped and atwhich the ca1ling-signals are received, and clearing-out annunciator-s,on which the clearing-out signals are received when the lines areconnected together for conversation.

5. In a telephone-exchange system, the combination, at the centraloffice, ofa switch-board at which is performed the switching between allthe lines which center at the oflice, two or more annunciator-boardsupon which the wires are grouped, each annunciator-board havingannunciators and contact-plates, one annunciator and one contact-platefor each line of its group, operators telephones, one for eachannunciator-board, each operators telephone being grounded on one sideand connected on the other side by a flexible cord with a metalliccontact-peg, and telephone-lines, each line passing first to theswitch-board, thence to its contactplate on the anininciator-board, andthence to its annunciator-magnet and to ground, as and forthe purposespecified.

MILO G. KELLOGG.

Witnesses:

Guns. A. BROWN, JAMEs L. BAIRD.

